Chmod 备忘清单
===
这份快速参考备忘单提供了文件权限的简要概述，以及 chmod 命令的操作
入门
--------
### 语法
```shell
$ chmod [options] <permissions> <file>
```
#### 示例
```shell
$ chmod 755 foo.txt
$ chmod +x quickref.py
$ chmod u-x quickref.py
$ chmod u=rwx,g=rx,o= quickref.sh
```
#### 递归更改文件和目录
```shell
$ chmod -R 755 my_directory
```
`chmod` 命令代表“更改模式”
### Chmod 生成器
```html preview
<div>
权限：<input type="text" id="num" placeholder="777" maxlength="3" style="padding: 0.3rem 0.3rem;" /> <input type="text" id="let" placeholder="rwxrwxrwx" maxlength="9" style="padding: 0.3rem 0.3rem;" />
</div>
```
---
| User | Group | Other
:- | :- | :- | :-
读 _(Read)_ | <input checked id="1" type="checkbox"></input> | <input checked id="4" type="checkbox"></input> | <input checked id="7" type="checkbox"></input>
写 _(Write)_ | <input checked id="2" type="checkbox"></input> | <input checked id="5" type="checkbox"></input> | <input checked id="8" type="checkbox"></input>
执行 _(Execute)_ | <input checked id="3" type="checkbox"></input> | <input checked id="6" type="checkbox"></input> | <input checked id="9" type="checkbox"></input>
<!--rehype:className=show-header-->
Chmod 生成器允许您以数字和符号的形式快速、直观地生成权限。
### 通用权限
命令 | s | 含义
:-|:-|:-
`400` | r-------- | 仅所有者可读
`500` | r-x------ | 避免改变
`600` | rw------- | 可由用户更改
`644` | rw-r--r-- | 由用户读取和更改
`660` | rw-rw---- | 可由用户和组更改
`700` | rwx------ | 只有用户具有完全访问权限
`755` | rwxr-xr-x | 只能由用户更改
`775` | rwxrwxr-x | 群组共享模式
`777` | rwxrwxrwx | 每个人都可以做任何事
### 解释
```shell
$ ls -l
-rw-r--r-- 1 root root 3 Jun 29 15:35 a.log
drwxr-xr-x 2 root root 2 Jun 30 18:06 dir
```
#### `dir` 的权限分析
```text
d rwx r-x r-x
┬ ─┬─ ─┬─ ─┬─
┆ ┆ ┆ ┆
┆ ┆ ┆ ╰─ 4. Other｜5 (4+0+1)
┆ ┆ ╰────── 3. Group｜5 (4+0+1)
┆ ╰─────────── 2. User ｜7 (4+2+1)
╰─────────────── 1. File Type | directory
```
### 权限模式
<!--rehype:wrap-class=col-span-2-->
| 权限 | 描述 | 八进制 | 十进制 |
|------------|-------------------------|-------|-----------|
`---` | 没有权限 | 000 | 0 (0+0+0)
`--x` | 执行 | 001 | 1 (0+0+1)
`-w-` | 写 | 010 | 2 (0+2+0)
`-wx` | 执行和写入 | 011 | 3 (0+2+1)
`r--` | 读 | 100 | 4 (4+0+0)
`r-x` | 读取和执行 | 101 | 5 (4+0+1)
`rw-` | 读和写 | 110 | 6 (4+2+0)
`rwx` | 读取、写入和执行 | 111 | 7 (4+2+1)
<!--rehype:className=show-header-->
### Objects
| 谁（缩写） | 含义 |
|-------------|--------------------|
| `u` | 用户 |
| `g` | 组 |
| `o` | 其它 |
| `a` | 全部，和 ugo 一样 |
<!--rehype:className=show-header-->
### 权限
| 缩写 | 权限 | 值 |
|--------------|---------------|-------|
| `r` | 读 | 4 |
| `w` | 写 | 2 |
| `x` | 执行 | 1 |
| `-` | 没有权限 | 0 |
<!--rehype:className=show-header-->
### 文件类型
| 缩写 | 文件类型 |
|--------------|----------|
| `d` | 目录 |
| `-` | 常规文件 |
| `l` | 符号链接 |
<!--rehype:className=show-header-->
Chmod 示例
--------
### 操作符
| Symbol | Description |
|--------|-------------|
| `+` | 添加 |
| `-` | 删除 |
| `=` | 设置 |
### chmod 600
```shell
$ chmod 600 example.txt
$ chmod u=rw,g=,o= example.txt
$ chmod a+rwx,u-x,g-rwx,o-rwx example.txt
```
### chmod 664
```shell
$ chmod 664 example.txt
$ chmod u=rw,g=rw,o=r example.txt
$ chmod a+rwx,u-x,g-x,o-wx example.txt
```
### chmod 777
```shell
$ chmod 777 example.txt
$ chmod u=rwx,g=rwx,o=rwx example.txt
$ chmod a=rwx example.txt
```
### 符号模式
<!--rehype:wrap-class=row-span-3-->
拒绝所有人的执行权限。
```shell
$ chmod a-x chmodExampleFile.txt
```
向所有人授予读取权限。
```shell
$ chmod a+r chmodExampleFile.txt
```
使文件可由组和其他人读写。
```shell
$ chmod go+rw chmodExampleFile.txt
```
使用户/所有者可执行 shell。
```shell
$ chmod u+x chmodExampleScript.sh
```
允许每个人读取、写入和执行文件并打开设置的 group-ID。
```shell
$ chmod =rwx,g+s chmodExampleScript.sh
```
### 删除权限
<!--rehype:wrap-class=row-span-3-->
要删除赋予文件的读写权限，请使用以下语法：
```shell
$ chmod o-rw example.txt
```
对于我们的文件 example.txt，我们可以通过运行以下命令使用 chmod for group 删除读写权限：
```shell
$ chmod g-rx example.txt
```
要从组中删除 chmod 读写权限，同时向 public/others 添加读写权限，我们可以使用以下命令：
```shell
$ chmod g-rx, o+rx example.txt
```
但是，如果你想删除组和其他人的所有权限，你可以使用 go= 来代替：
```shell
$ chmod go= example.txt
```
### 可执行文件
```shell
$ chmod +x ~/example.py
$ chmod u+x ~/example.py
$ chmod a+x ~/example.py
```
### chmod 754
```shell
$ chmod 754 foo.sh
$ chmod u=rwx,g=rx,o=r foo.sh
```
Chmod 实践
---------------
### SSH 权限
```shell
$ chmod 700 ~/.ssh
$ chmod 600 ~/.ssh/authorized_keys
$ chmod 600 ~/.ssh/id_rsa
$ chmod 600 ~/.ssh/id_rsa.pub
$ chmod 400 /path/to/access_key.pem
```
### 网络权限
```shell
$ chmod -R 644 /var/www/html/
$ chmod 644 .htaccess
$ chmod 644 robots.txt
$ chmod 755 /var/www/uploads/
$ find /var/www/html -type d -exec chmod 755 {} \;
```
### 批量更改
```shell
$ chmod -R 644 /your_path
$ find /path -type d -exec chmod 755 {} \;
$ find /path -type f -exec chmod 644 {} \;
```
请参阅：[命令替换](https://tldp.org/LDP/abs/html/commandsub.html)
另见
----
* [使用 chmod 修改文件权限](https://www.linode.com/docs/guides/modify-file-permissions-with-chmod/) _(linode.com)_
<!--rehype:ignore:start-->
以下是 Chmod 生成器 JS 代码（代码用于网站请忽略不要删除）
---
<!--rehype:ignore:end-->
```html preview
<!-- Chmod 生成器 JS 代码 -->
<script type="text/javascript">
const reg_num = /^[0-7]{3}$/; // 一些正则表达式来检查 num 输入
const reg_let = /^([r\-]{1}[w\-]{1}[x\-]{1}){3}$/; // 一些正则表达式来检查文本输入
function checkBoxHandle() {
change_occured(true, false, false);
// get rid of bad input classes
document.getElementById('num').classList.remove('bad-input');
document.getElementById('let').classList.remove('bad-input');
}
window.addEventListener("DOMContentLoaded", function () {
// loop over all the check boxes
for (let i = 1; i < 10; i++) {
let checkBox = document.getElementById(`${i}`);
checkBox.addEventListener('change', function () {
change_occured(true, false, false);
// get rid of bad input classes
document.getElementById('num').classList.remove('bad-input');
document.getElementById('let').classList.remove('bad-input');
});
}
// the octal input
let num_input = document.getElementById('num');
let num_fn = function () {
// check for bad input
if (!reg_num.test(this.value)) {
this.classList.add('bad-input');
} else {
this.classList.remove('bad-input');
change_occured(false, true, false);
}
};
num_input.addEventListener('change', num_fn);
num_input.addEventListener('keyup', num_fn);
// the let input
let let_input = document.getElementById('let');
let let_fn = function () {
// check for bad input
if (!reg_let.test(this.value)) {
this.classList.add('bad-input');
} else {
this.classList.remove('bad-input');
change_occured(false, false, true);
}
};
let_input.addEventListener('change',let_fn);
let_input.addEventListener('keyup',let_fn);
});
/* SETUP
r-4-1 r-4-4 r-4-7
w-2-2 w-2-5 w-2-8
x-1-3 x-1-6 x-1-9
*/
// define a function that runs when a change occures
function change_occured(caller_was_check, caller_was_num, caller_was_let) {
let num1 = 0, num2 = 0, num3 = 0; // these are the three numbers for the octal
let perm_string = ''; // holds the permision string ex. rw-x--r--
if (caller_was_check) {
// loop over all the check boxes and get the permisions
for (let i = 1; i < 10; i++) {
let checkBox = document.getElementById(`${i}`);
if (checkBox.checked) { // if checked
let current_perm = check_to_octal_and_text(i);
perm_string += `${current_perm.perm_let}`;
if (i <= 3) {
num1 += current_perm.perm_num;
} else if (i <= 6) {
num2 += current_perm.perm_num;
} else {
num3 += current_perm.perm_num;
}
} else { // if not checked
perm_string += '-';
}
}
// set the permision input text
document.getElementById('let').value = perm_string;
document.getElementById('num').value = `${num1}${num2}${num3}`;
} else if (caller_was_num) {
// get the individual numbers
let num_input_val = document.getElementById('num').value;
num1 = num_input_val.substring(0, 1);
num2 = num_input_val.substring(1, 2);
num3 = num_input_val.substring(2, 3);
// set the checkboxes and get the perm string
perm_string += octal_to_check_and_txt(num1, 0); //Owner
perm_string += octal_to_check_and_txt(num2, 1); //Owner
perm_string += octal_to_check_and_txt(num3, 2); //Owner
// set the permision input text
document.getElementById('let').value = perm_string;
} else if (caller_was_let) {
// get the text input
let perm_text = document.getElementById('let').value;
num1 = text_to_check_and_octal(perm_text.substring(0, 3), 0)
num2 = text_to_check_and_octal(perm_text.substring(3, 6), 3)
num3 = text_to_check_and_octal(perm_text.substring(6, 9), 6)
// set the octal value
document.getElementById('num').value = `${num1}${num2}${num3}`;
}
}
// define a function to converts the checkbox # to the respective permissions
// returns perm_num, perm_let
function check_to_octal_and_text(check_num) {
let perm_num = 0;
let perm_let = '-';
switch (check_num) {
case 1:
case 4:
case 7:
perm_num = 4;
perm_let = 'r';
break;
case 2:
case 5:
case 8:
perm_num = 2;
perm_let = 'w';
break;
case 3:
case 6:
case 9:
perm_num = 1;
perm_let = 'x';
break;
default:
perm_num = 0;
perm_let = '-';
}
// return values
return {
perm_num,
perm_let
};
}
/**
Takes a number 1-7 and which class it is in:
0 = owner
1 = Group
2 = Public
Returns: perm text (ex. "rwx") and sets the appropriate checkboxes
*/
function octal_to_check_and_txt(octal_num, class_num) {
let perm_text = '';
let offset = class_num * 3;
switch (octal_num) {
case '1':
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = '--x';
break;
case '2':
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = '-w-';
break;
case '3':
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = '-wx';
break;
case '4':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = 'r--';
break;
case '5':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = 'r-x';
break;
case '6':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = 'rw-';
break;
case '7':
document.getElementById(`${1 + offset}`).checked = true;
document.getElementById(`${2 + offset}`).checked = true;
document.getElementById(`${3 + offset}`).checked = true;
perm_text = 'rwx';
break;
default:
document.getElementById(`${1 + offset}`).checked = false;
document.getElementById(`${2 + offset}`).checked = false;
document.getElementById(`${3 + offset}`).checked = false;
perm_text = '---';
}
return perm_text;
}
/**
Takes 3 letters (r, w, x, - ex. 'rw-') and an offset (0,3,6)
Returns the octal num and sets the appropriate checkboxes
*/
function text_to_check_and_octal(letters, offset) {
let perm_num = 0; // the octal number to return
// add up the oct num and set the check boxes
for (let i = 0; i < 3; i++) {
current_let = letters.substring(i, i + 1);
if (current_let == 'r') {
document.getElementById(`${i + 1 + offset}`).checked = true;
perm_num += 4;
} else if (current_let == 'w') {
document.getElementById(`${i + 1 + offset}`).checked = true;
perm_num += 2;
} else if (current_let == 'x') {
document.getElementById(`${i + 1 + offset}`).checked = true;
perm_num += 1;
} else {
document.getElementById(`${i + 1 + offset}`).checked = false;
}
}
return perm_num;
}
</script>
```